Potential for carbon sequestration in reclaimed mine soil on reforested surface mining areas in Poland

Reclaimed mine soils (RMS) which develop on post-mining sites play significant role in Carbon sequestration in new ecosystems, especially in local range on areas disturbed by human activity. This study presents the potential for Carbon sequestration in RMS developing on 3 post sur- face mining areas in Poland (Central Europe) reforested with Scots pine (Pinus sylvestris L). Research was conducted on waste heaps and quarry which accompany open cast lignite, sul- fur, and sand mining. Control plots were arrang- ed in managed pine forests on natural sites in the surrounding area. The results shows high Carbon accumulation in RMS, estimated on 16.77 Mg?ha-1 in poor (oligotrofic) soils on Quaternary sands on sand quarry and up to 65.03 Mg?ha-1 on external waste heap after Sulfur sur- face mining exploitation on Quaternary sands mixed with Tertiary clays. These results were very similar to natural forest soils on control plots. Potential rate of Carbon sequestration in RMS was estimated on 0.73 (on the poorest sa- ndy soils on quarry) to 2.17 Mg?ha-1?yr-1 (on potentially abundant sandy-clayish soils on Sulfur waste heap), and 5.26 Mg?ha-1?yr-1 (on Tertiary sands substrate soils on lignite mining waste heap). In conslusion the average Carbon accu- mulation in RMS was estimated on 41 Mg?ha-1 and Carbon sequestration rate was 1.45 Mg? ha-1?yr-1. According to the result of this study and range of post-mining areas reclaimed to forestry in Poland (ca 15000 ha) total Carbon accumulation in RMS was estimated on 615 × 103 Mg and potential Carbon sequestration rate in new ecosystems on 21.75 × 103 Mg?ha-1?yr-1. However, the main factors affecting Carbon sequestration and protection in RMS under tree stand were substrate, percentage of clay and silt sized fraction, in order to formulate guidelines for sustainable management of post-mining ec- osystem, further study must be continue for be- tter understanding.

Effectivity of arbuscular mycorrhizal fungi collected from reclaimed mine soil and tallgrass prairie

We examined suitability of arbuscular mycorrhizal fungi (AMF) associated with cool-season nonnative forages on reclaimed surface-mined land in southeast Ohio for establishment of native warm-season grasses. The goal of establishing these grasses is to diversify a post-reclamation landscape that is incapable of supporting native forest species. A 16-week glasshouse study compared AMF from a 30-year reclaimed mine soil (WL) with AMF from native Ohio tallgrass prairie soil (CL). Four native grasses were examined from seedling through 16 weeks of growth. Comparisons were made between CL and WL AMF on colonized (+AMF) and non-colonized plants (–AMF) at three levels of soil phosphorus (P). Leaves were counted at 4 week intervals. Shoot and root biomass and percent AMF root colonization were measured at termination. We found no difference between WL and CL AMF. Added soil P did not reduce AMF colonization, but did reduce AMF efficacy. Big bluestem (Andropogon gerardii Vitman), Indiangrass (Sorghastrum nutans (L.) Nash), and tall dropseed (Sporobolus asper (Michx.) Kunth) benefited from AMF only at low soil P while slender wheatgrass (Elymus trachycaulus (Link) Gould ex Shinners) exhibited no benefit. Establishment of tallgrass prairie dominants big blue-stem and Indiangrass would be supported by the mine soil AMF. It appears that the non-native forage species have supported AMF equally functional as AMF from a regionally native tallgrass prairie. Tall dropseed and slender wheatgrass were found to be less dependent on AMF than big bluestem or Indiangrass and thus would be useful in areas with little or no AMF inoculum.

Soil properties in reclaimed farmland by filling subsidence basin due to underground coal mining with mineral wastes in China

Reclaimed mining-induced subsidence area soils (RMSs) could restore soil quality and crop productivity in coal mining area. This study was conducted to evaluate the effects of mineral-processing wastes (fly ash vs coal gangue) as backfill substrates on soil chemical and microbial properties in mining-induced subsidence area. A general higher water holding capacity (WHC) and pH had been observed in fly ash than coal gangue reconstructed soil. Soil microbial biomass C (MBC) and N (MBN), MBC/TOC (total organic carbon) ratio (qmic) were higher under the influence of the fly ash, while contents of As, Cr, C/Nbio, the basal respiration per unit of microbial biomass (QCO2) were higher under the coal gangue reconstructed mode in 0-10, 10-20, 20-50 cm layers. The microbial basal respiration was higher in 0-10, 10-20, 0-50 cm layers, while was lower in 20-50 cm layer under fly ash than that of coal gangue reconstructed mode. The lower QCO2 of fly ash mine soil suggested the lower maintenance energy requirement of the microbial community. Moreover, the contents of metals may possibly have negative implications for soil microbial and enzyme activities in reconstructed soil.

Assessment of Soil Contamination and Human Health Risk around an Industrial Gold Mine in Côte d’Ivoire: The Case of Arsenic

The Tongon mine generates millions of tons of waste rock and tailings, which are stored in landfills in the vicinity of the mine. These tailings contain arsenic. The risk of soil contamination in this area is evident. This study assesses the arsenic contamination of soils around the mine and the health risks to the local population. Soil samples were taken from plastic bags and other materials used as working tools. Arsenic concentrations were determined by inductively coupled plasma mass spectroscopy, after the soil samples had been concentrated and digested. Metal contamination indices were used to assess the degree of soil contamination. The results obtained indicate that soils in the industrial zone of the Tongon gold mine have very high average concentrations, well above the world average for uncontaminated soils of 6 mg/kg arsenic. Geoaccumulation index values range from 1.28 to 3.40. These values highlight severe arsenic soil contamination. The human health risk assessment revealed that exposure risks are well above the critical limit of 1 and are, in descending order, children > adult women > adult men. These results indicate an ecological risk, requiring environmental monitoring, underpinned by the development of an effective remediation strategy to reduce local pollution and contamination.

Transport patterns and numerical simulation of heavy metal pollutants in soils of lead–zinc ore mines

Exploring transport patterns of soil contaminants is essential for solving the problem of heavy metal contamination in mine soils.In this study,contamination of Pb,Zn,and Cd in the mountain soils of the lead–zinc ore mines in Ganxi Township,Hengdong County,Hunan Province,China was investigated,and their transport patterns were further explored using a soil-column model and numerical simulation techniques.In total,111 mine soil samples were collected and placed into six experimental soil columns.By controlling the water flow,a control soil column group(CK),two mixed soil columns X1 with daily water flows of 1 and 5 L,and three mixed soil columns X3 with daily water flows of 2,3,and 4 L were evaluated.The results showed that the residual fraction of Pb accounted for 71.93%of the content on average,whereas the exchangeable fractions of Zn,Cd,and Fe-Mn oxide-bound fractions of Zn and Cd accounted for 28.60%,31.07%,and 43.2%and 53.54%of the content,respectively.Pb,Zn,and Cd in the soils of the CK,X1,and X3 groups mainly were accumulated at a depth from approximately 0 to 20 cm,and the content at this depth accounted for 60.09%of that at a 0~40 cm depth.The soil at a depth range of 0~10 cm was most seriously contaminated,and the proportion of content was 32.39%of that at a 0~40 cm depth.Numerical simulation showed that on the 5 th day,the pollutant transport range was 0~24 cm,and on the 9 th day,the pollutant transport range exceeded 40 cm.On the 15 th day,the transport capacity of pollutants at depths of 0~40 cm was close to the stable state,but the soil at a depth of 0~10 cm was still heavily polluted.These results reflect the transport pattern of heavy metal pollutants in the soil of lead–zinc ore mines and may provide a reliable scientific support for the prevention of heavy metal contamination in mine environments.

Biochar compost blends facilitate switchgrass growth in mine soils by reducing Cd and Zn bioavailability

Biochars have the potential to reclaim mine-impacted soils;however,their variable physico-chemical properties incite specu-lation about their successful remediation performance.This investigation examined the capability of biochars produced from three different feedstocks along with a compost blend to improve switchgrass growth conditions in a mine-impacted soil by examining influences on soil pH,grass metal contents,and soil-extractable metal concentrations.Cadmium(Cd)-and zinc(Zn)-contaminated mine soil was collected from a site near Webb City,Missouri,USA-a location within the Tri-State Min-ing District.In a full factorial design,soil was treated with a 0%,2.5%,and 5%(w/w)compost mixture(wood chips+beef cattle manure),and 0%,2.5%and 5%of each biochar pyrolyzed from beef cattle manure,poultry litter,and lodgepole pine feedstocks.Switchgrass(Panicum virgatum,‘Cave-In-Rock’variety)was grown in a greenhouse for 50 days and the mass of shoots(above-ground biomass)and roots was assessed,while soil pH,deionized H_(2)O-and 0.01 M CaCl_(2)-extractable Cd and Zn concentrations were measured.Poultry litter biochar and compost had the greatest ability to raise soil pH(from 4.40 to 6.61),beef cattle manure biochar and compost moderately raised pH(from 4.4 to 5.92),and lodgepole pine biochar and compost weakly raised pH(from 4.40 to 5.05).Soils treated with beef cattle manure biochar,poultry litter biochar signifi-cantly reduced deionized H_(2)O-and 0.01 M CaCl_(2)-extractable Cd and Zn concentrations,while lodgepole pine biochar-treated soils showed mixed results.Switchgrass shoot and root masses were greatest in soil treated with compost in combination with either beef cattle manure biochar or poultry litter biochar.Soils treated with 5%beef cattle manure biochar+5%compost had greater reductions in total Cd and Zn concentrations measured in switchgrass shoots and roots compared to the other two treatments.The three biochars and compost mixtures applied to heavy metal,mine-impacted soil had considerable performance dissimilarities for improving switchgrass productivity.Switchgrass growth was noticeably improved after treatment with the compost in combination with biochar from beef cattle manure or poultry litter.This may be explained by the increased soil pH that promoted Zn and Cd precipitation and organic functional groups that reduced soil-available heavy metal concentrations.Our results imply that creating designer biochars is an important management component in developing successful mine-site phytostabilization programs.

Effect of combined pollution by heavy metals on soil enzymatic activities in areas polluted by tailings from Pb-Zn-Ag mine

Some enzymatic activities were determined in the areas polluted by tailings from Tiantai Pb-Zn-Ag Mine in Zhejiang Province of China. The results indicated the soil enzymatic activities decreased significantly with increase of concentrations of heavy metals or the distance away from mining tailing center, especially dehydrogenase and urease activities. Multivariate regression analysis between heavy metal contents and soil enzymatic activities indicated that single dehydrogenase activity was very significantly correlated to combined effect of soil heavy metals in mine area. Moreover, single urease, protease and acid phosphatase activities were significantly related to the combined effect of heavy metals. The results suggest it is feasible to use soil enzymatic activities to indicate the pollution situation by combined heavy metals in the soil of mine area.

Risk assessment of heavy metal contaminated soil in the vicinity of a lead/zinc mine

Heavy metal contamination of soils through anthropogenic activities is a widespread and serious problem confronting scientists and regulators throughout the world. In this study we investigated the distribution, chemical species and availability of lead, zinc, cadmium and copper in nine surface（0 to 20 cm） soils from near an abandoned lead/zinc mine tailings located in Shaoxing, Zhejiang, China. Total heavy metal contents ranged from 5271 to 16369 mg/kg for Pb, 387 to 1221 mg/kg for Zn, 3.0 to 9.3 mg/kg for Cd and 65 to 206 mg/kg for Cu. In general, all heavy metals exceeded China National Standards for Soil Environmental Quality of Heavy Metals by a factor of 3-65 times. Comparison of the heavy metal concentrations（Pb, Zn, Cd and Cu） with clay content revealed a strongly significant relationship while significant relationship（ P 〈 0.001 ） was also obtained between Cd ＋ Zn and Pb ＋ Cu. Solid phase speciation of the soils using Tessier procedure showed that the heavy metals were distributed in the order： residual 〉〉 organically complexed-Fe-Mn oxides occluded 〉 carbonate bound 〉 exchangeable 〉 water soluble. In the organic matter fraction, the ratio of Pb（29.1% ） to its total concentration in the soils was higher than those of Zn（4.70% ）, Cd（3.16% ） and Cu（9.50% ）. The percentages of the water soluble and the exchangeable fractions of Pb（1.80% ） and Cd（2.74% ） were markedly greater than those of Zn（0.10% ） and Cu（0.15% ）, suggesting that Pb and Cd are relatively more mobile and hence more toxic in the contaminated soils. Strongly significant relationships between H20-Pb, H20-Zn and H20-Cu, strong positive correlations between H20-Pb, H20-Zn, H20-Cu and organic matter in soil were found. The content of H20-Pb, H20-Zn, H20-Cu was negatively correlated with pH values. The similar negative relationships between pH values and exchangeable heavy metals were also recorded. It is suggested that increasing soil pH or liming the soil could decrease bioavailability of heavy metals in the soil.

Evaluation of Quality of Some Rehabilitated Mined Soils within the AngloGold-Ashanti Concession in Ghana

Land degradation caused by surface mining of gold has been extensive in Ghana. In recent years rehabilitation of some degraded lands by re-vegetation has been undertaken. This study provides quantitative data on the quality of some rehabilitated and un-rehabilitated mined soils within the AngloGold-Ashanti gold concession in parts of the semi-deciduous forest zone of Ghana. Soil properties determined included texture, bulk density and aggregate stability, pH, organic carbon, available phosphorus, total nitrogen, cation exchange capacity, exchangeable bases, exchange acidity, Fe, Mn, Ni, Cu, Zn, Cd, and Pb. Aggregate stability as a physical quality indicator revealed that aggregates of the rehabilitated mined soil had become more stable and similar to the control unmined soil due to litter and carbon additions from planted trees. The nutrient levels were very low because of the presence of low activity clays inherent in the native soil. Organic carbon content in the rehabilitated soil had increased above that of the unrehabilitated soil. Variability in soil properties, especially organic carbon and aggregate stability, was minimal in the unmined and rehabilitated soils implying that soils at the two sites were most robust and resistant to crushing and rupture. Quality index of the unmined control soil was 36.5% indicating that the quality of the soil was 63.5% relative to the optimum quality because of inherent poor soil properties. The mined rehabilitated and unrehabilitated soil had index values of 32.5% and 24.4 %, respectively. The marginal difference of 4% in soil quality between the control and rehabilitated soil shows that it is possible to maintain the health of soils with inherent physical and biochemical deficiencies if reclamation regulations are adhered to. In this way, the socio-economic dilemma of exploiting natural resources for the benefit of societies is ameliorated while maintaining an ecosystem balance.

Heavy metal concentrations in soils and plants in the vicinity of Arufu lead-zinc mine, Middle Benue Trough, Nigeria

This study focused on the influence of base metal mining on heavy metal levels in soils and plants in the vicinity of Arufu lead-zinc mine, Nigeria. Soil samples (0-15 cm depth) and plant samples were collected from cul-tivated farmlands in and around the mine, the unmineralized site and a nearby forest (the control site). The samples were analyzed for heavy metals (Fe, Zn, Mn, Cu, Pb, Cr and Cd) by Atomic Absorption Spectrophotometry (AAS). The physical properties of soils (pH and LOI) were also measured. Results showed that soils from cultivated farm-lands have neutral pH values (6.5-7.5), and low organic matter contents (<10%). Levels of Zn, Pb and Cd in culti-vated soils were higher than the concentrations obtained from the control site. These heavy metals are most probably sourced from mining and agricultural activities in the study area. Heavy metal concentrations measured in plant parts decreased in the order of rice leaves>cassava tubers>peelings. In the same plant species, metal levels decreased in the order of Zn>Fe>Mn>Cu>Pb>Cr>Cd. Most heavy metals were found in plant parts at average concentrations normally observed in plants grown in uncontaminated soil, however, elevated concentrations of Pb and Cd were found in a few cassava samples close to the mine dump. A stepwise linear regression analysis identified soil metal contents, pH and LOI as some of the factors influencing soil-plant metal uptake.

Effects of Fertilization Type on Carbon Storage of Soil and Crops in Mine Wasteland

Taking a three-year fertilization trial in mine reclamation soil from Shanxi Province, China as an example, the effects of different fertilization treatments on soil carbon storage and carbon fixation by corn were studied in this paper. Four treatments were designed in the experiment, including fertilizer （ F）, organic manure （ M）, half organic manure plus half fertilizer （ FM） and control （CK）. The results showed that fertilization had certain roles in increasing organic carbon storage of mine reclamation soil, and the application of single or combined organic and inorganic fertilizers had the most remarkable influence. Meanwhile, the treatment of single or combined organic and inorganic fertilizers could improve the carbon fixation capacity of corn prominently, and increased soil organic matter input. Thus, the application of organic manure or combined organic and inorganic fertilizer has great contribution to enhancing soil carbon sink and sustainable development of agriculture. However, the combined application of organic and inorganic fertilizer is the best choice for agricultural field based on economic consideration.

Quantitative analysis of biotechnical reinforcement for a steep slope consisting of composite coal-gangue-soil medium adjacent to a mined-out area

The engineering and geological characteristics of a steep slope consisting of coal gangue, rock and soil medium in Huating coal mine have been comprehensively investigated. Owing to humid weather, heavy rainfall, vegetation and porous characteristics of the soil and rock mass, the steep slope will be destabilized and induce mud-rock flow or derive hazard easily. Firstly, based on the classical slope reinforcement theory, some regularity between the shear and displacement in the destabilized zone of the slope with or without root strength contribution is presented. Then, based on the experimental and statistical analysis of root strength, hydrological characteristics and stability status, etc., some possible biotechnical techniques for reinforcement of the steep slope have been suggested. These methods are important for quantitative analysis of destabilization of the slope and design of the biotechnical reinforcement.

安徽矾矿土壤重金属污染源解析模型对比与优选

矿区资源开采导致土壤污染日益严重,直接影响周边土壤、水体环境的稳定性,精准预测重金属污染源解析对矿山修复、治理具有重要指导作用。在前期研究基础上,为提升土壤介质模型的解释度,进一步选取了土壤重金属源解析评价中成熟度高且精准性好的正定矩阵因子分析法(positive matrix factorization, PMF)及绝对因子分析-多元线性回归(absolute factor analysis-multiple linear regression, APCS-MLR)模型,以充实前期UNMIX多元受体模型分析矾矿土壤重金属污染来源及源贡献率的结果,结合生态风险评价方法,对比定量条件下最适宜解析研究区域源的模型。结果表明:1)生态高风险区域主要集中在研究区南部和东部,Cd是矿山主要风险元素,地累积指数(index of geoaccumulation)均值3.75与潜在生态风险指数(potential ecological risk index)均值731.22解析结果高度一致,但潜在生态危害指数的结果综合性更好。2)对比3种模型的污染源解析结果,PMF模型解析出4个污染源:分别为燃煤源、自然-交通综合源、自然源和大气沉降源,源贡献率分别为38.15%、20.62%、24.28%、16.95%。3)PMF模型的总体变量拟合优度R2达到了0.96,拟合效果最好。PMF模型模拟数据会集中采样点误差,确定最适污染源数目及相应污染物贡献率,使得源解析结果更精准,更适用于复杂的矿山污染土壤情况,符合实际研究情况。该研究结果可为后续矿区开采后污染土壤的修复治理工作提供溯源依据参考。

Soil quality index as a tool for Scots pine(Pinus sylvestris) monoculture conversion planning on afforested,reclaimed mine land

In Central Europe, a large portion of post-mining sites were afforested with Scots pine, which is characterized by good adaptability and a tolerance for poor habitat at the beginning of forest ecosystem development. Conversion of monoculture on mine sites into more biodi- verse mixed hardwood forests, especially on more fertile deposits, can be an emerging need in this part of Europe in next decades. The ability to classify the forests at these post-mining sites will facilitate proper species selection as well as the management and formation of the developed ecosystem＇s stability. This work describes the guidelines that can be followed to assess reclaimed mine soil （RMS） quality, using the mine soil quality index （MSQI） and a classification of developed forest sites as a basis of tree-stand species selection and conversion of pine monocul- tures. The research was conducted on four post-mining facilities （lignite, hard coal, sulphur, and sand pit mining areas） on different RMS sub- strates dominant in Central Europe. Soil quality assessment takes into account the following features of the soil： texture soil nutrients （Ca, Mg, K, Na, P）; acidity （pH KC1）; and Corg-to-Nt ratio in the initial organic horizon. An analysis was conducted of classification systems using the MSQI validation correlation （at p =0.05） with vegetation features af- fected by succession： aboveground biomass of forest floor and ecological indicators of vascular plants （calculated on the basis of EUenberg＇s （2009） system）. Eventually, in the analysed data set, the MSQI ranged from 0.270 for soils on quaternary sands to 0.720 for a mix of quaternary loamy sands with neogene clays. Potential forest habitat types and the role of the pine in the next generation of tree stands on different RMS parent rock substrate were proposed.

Availability of Residual and/or Applied Inorganic Phosphorus for Sugarcane Uptake and Growth in a Post-Mined Reconstituted Soil

Mineral sands mining is worldwide an environmental issue and also at the Hillendale mine in KwaZulu-Natal, South Africa. The post-mined soil is to be rehabilitated to sugarcane cropping. One of the concerns with the post-mined soil which is reconstituted with a 70:30 mixture of sand: slimes (silt-plus-clay fraction), is its low phosphorus (P) status, which could be limiting for optimum sugarcane production. A field experiment was conducted on a reconstituted soil at Hillendale to establish the availability of either residual or applied inorganic P to the plant and first ratoon sugarcane crop. Four treatments were evaluated including those where P fertilizer was omitted, applied at half the recommended rate or introduced equal to the recommended rate according to chemical analysis of the soil. In the fourth treatment, no fertilizer was applied at all, whereas nitrogen (N) and potassium (K) were added at recommended rates in the first three treatments. Phosphorus application had a significant effect on sugarcane fractional light interception and aboveground biomass yield of the plant and first ratoon crops, and stalk length and diameter of the first ratoon crop. Pol, brix, purity and fibre content and tiller number were not affected by P application. The application of P increased the foliar N, P, K, calcium (Ca), magnesium (Mg) and sulphur (S) contents of both crops. However, foliar N, P and K were deficient in the first ratoon crop even in the case where fertilizer was applied at the recommended rates, which could have been because of waterlogging. The possible effect of waterlogging on P uptake needs to be addressed in future studies in this reconstituted soil.

基于CWT-CARS-CNN综合方法的矿区土壤煤源碳质量分数高光谱估测

目的目前,尚无可靠方法定量识别土壤中煤源碳,为此,方法采集焦作矿区耕地土壤,配制249个不同质量分数的煤源碳土壤样品,利用ASD FieldSpec4获取样品光谱数据,采用连续小波变换(continuous wavelet transform,CWT)-竞争性自适应重加权采样(competitive adaptive reweighted sampling,CARS)-卷积神经网络(convolutional neural networks,CNN)方法估测土壤中煤源碳质量分数,并对比CWT-CARS-CNN方法与传统光谱指数法构建的煤源碳估测模型估测效果,检验CWT-CARS-CNN估测模型的适用性。结果结果表明:350~2500 nm波段内,煤与土壤光谱特征截然不同,含煤土壤样品光谱反射率随煤源碳质量分数增加而降低;CWT方法提高了光谱对土壤煤源碳的敏感性,CARS方法提取的煤源碳敏感波段数量明显增加,基于CWT-CARS-CNN方法的煤源碳质量分数估测模型精度明显高于传统光谱指数法的;以L8分解尺度构建的CWT-CARS-CNN模型精度最高,验证集R2=0.9993,RPD=40.3081。结论基于CWT-CARS-CNN的高光谱估测方法能较准确地估测矿区不同土地利用类型下土壤中的煤源碳质量分数,可为“双碳”背景下矿区土壤碳固存与肥力评估提供参考。

风流扰动下露天矿土质路面粉尘运移规律研究

为降低露天矿土质路面粉尘质量浓度,提高清洁生产水平,采用气固两相流理论,建立粉尘颗粒起动模型,分析粉尘起动风速及变化规律,利用实验研究进行验证,并确立粉尘运移规律以及运动形式,选取正交实验极差分析各因素对起尘量影响显著性。研究结果表明:粉尘起动风速与粉尘粒径、含水率、负荷均有函数关系;起尘量在粒径、含水率、负荷、风速4种因素下呈现不同变化规律,与粒径、风速均呈非线性关系,与含水率呈负相关,与粉尘负荷呈正相关,影响显著性为:粒径>负荷>风速>含水率;粉尘运动形式与风速和粒径相关,在5 m/s风速下,(0,75]μm粒径粉尘易做悬浮运动,(75,500]μm粒径粉尘易做跳跃运动,(500,1000]μm粒径粉尘易做蠕移运动。研究结果可为降尘措施提供理论指导。

Artisanal Mining and Soil Quality in the Sudano-Sahelian Climate: Case of the Artisanal Mining Site of Yimiougou in Burkina Faso, West Africa

The majority of the population of Burkina Faso lives from agriculture and therefore depends on the land. The main objective of this study is to assess the quality of the soils in the area linked to artisanal mining activities. The methodology adopted consisted in sampling and characterizing the main types of soil. In order to assess the level of soil pollution by artisanal mining, parameters such as the geo-accumulation index (Igeo) and the contamination factor (CF) are calculated. A prediction of acid mine drainage (AMD) was also carried out on samples of mine tailings which are potential sources of pollution of these soils. The results obtained show that the soils in Yimiougou are of nil to low agronomic interest. The Igeo shows that for lead, copper, zinc and arsenic the levels found in the different morphological units are partly attributable to human action and specifically artisanal mining. The values of the contamination factor indicate contamination. Cobalt presents the lowest contamination. For cadmium, the different types of soil are moderately contaminated except for the FITLC type, which has a CF value of 0.50, therefore synonymous with low or absent contamination. The various morphological units studied are very heavily contaminated with zinc, copper, lead and arsenic. The pH and conductivity values indicate that the mine tailings samples are non-acidogenic, therefore not yet oxidized. As for the sulphide contents, they show that only samples S17, S22, S23 and S24 present values that are strictly above the threshold (0.3%) and therefore potentially acid-generating. The comparative study of the acid potential (AP) and the neutralization potential (NP) reveals that the neutralization potentials of the different samples are clearly higher than the acid potentials even for the samples which present a proven acidification potential (S17, S22, S23 and S24). These results show that the mine tailings have the natural capacity to neutralize any possible mine drainage, given the presence of acid-eating minerals such as the carbonates associated with the mineralization.

基于土壤肥力恢复力模型的河曲露天煤矿复垦治理效果评价

以河曲旧县露天煤矿排土场为研究对象,采用模糊层次分析法(FAHP)和专家评分理论法建立了露天煤矿排土场土壤肥力综合评价模型,获得土壤结构稳定性、土壤保水能力、土壤保肥能力及土壤生物活性4项准则和25个因素,利用YAAHP计算软件确定了排土场土壤肥力恢复力各影响因素的权重。结果表明,评价体系准则层中土壤保肥能力权重最大(0.5477),其次分别是土壤保水能力(0.1980)、土壤生物活性(0.1408)和土壤结构稳定性(0.1135),因素层有机质F1权重最高(0.1162);根据现场抽样,已复垦区的土壤质量水平要高于未复垦区的土壤质量水平,整体来看土壤质量水平均处于中等偏下和较差水平,土壤恢复力的主要因素是土壤保肥能力,特别是土壤有机质含量。土壤肥力恢复力模型为提高排土场土壤质量、加快土壤重构、促进土壤生态系统恢复提供治理思路。

干旱矿区利用夏季和上年秋季土壤种子库恢复植被研究

【目的】针对西部干旱矿区实际情况,探究该地区表土资源中土壤种子库的可利用性以及制约因素,筛选出有效的利用模式,为矿区植被恢复提供理论依据和技术参考。【方法】对内蒙古自治区乌海市新星矿区周边低扰动区域的表土在上年度10月(秋季)和当年6月(夏季)进行剥离,采用覆土厚度、补种量和每日灌溉量3因素3水平的正交试验对不同季节表土中土壤种子库萌发效果影响进行研究,并结合生态和经济效益,评选出适宜干旱矿区植被恢复的技术组合。【结果】(1)10月土壤种子库萌发植物数量为(83.72±10.88)株/m^(2),物种共出现20种,6月土壤种子库萌发植物数量为(44.83±8.96)株/m^(2),物种共出现13种。秋季土壤种子库密度和物种丰富度均高于夏季土壤种子库。(2)灌溉对秋季土壤种子库萌发影响最重要,其次是覆土厚度,最后是补种。3种因素对夏季土壤种子库萌发影响程度基本相同。(3)覆土厚度因素对两组土壤种子库的植被覆盖度、群落高度物种丰富度的影响显著(P<0.05)。灌溉量对两组土壤种子库萌发植物数量、植被覆盖度和群落高度的影响显著(P<0.05)。补种因素未对两组任何相同指标产生显著影响。【结论】干旱矿区排土场植被恢复最优实施方案组合:利用秋季剥离的表土,覆土厚度2 cm,补种量50粒/m^(2),每日灌溉量2 L/m^(2)。该结论可为今后矿区植被恢复提供技术参考。